The Greenland ice sheet is almost pure water formed by countless centuries of snowfall, whereas Europan ice contains high levels of sodium chloride. is whether their mechanism for double ridge formation could work with salty ice,” he says. However, it's far from an open-and-shut case. is very compelling,” says Kevin Hand (Jet Propulsion Laboratory, Caltech), who was not involved in the research. NASA's planned Europa Clipper mission sails over the icy surface of Jupiter's moon Europa in this illustration. “That would suggest there could be a reasonable amount of exchange happening inside of the ice shell,” Culberg says. Similar shallow water pockets could form on Europa when water from the subsurface ocean is forced up into the ice shell through fractures. “People have been studying these double ridges for over 20 years now, but this is the first time we were actually able to watch something similar on Earth and see nature work out its magic,” says team member Gregor Steinbrügge. The ice then fractures around a pocket of pressurized water as it refreezes inside the ice sheet. “In Greenland, formed in a place where water from surface lakes and streams frequently drains into the near-surface,” says lead researcher Riley Culberg. When the team analyzed surface elevation data and ice-penetrating radar, collected in Greenland from 2015 to 2017 by NASA’s Operation IceBridge, they saw similar double ridges to those observed on the icy surface of Europa. The team was trying to understand the Greenland ice in order to improve future sea-level predictions in the face of global warming. “We were working on something totally different related to climate change and its impact on the surface of Greenland,” Schroeder says. The Stanford team may have just solved the riddle of how they formed thanks to observations made considerably closer to home. This high-resolution image of Europa's icy crust, also taken by Galileo, reveals a surface criss-crossed by multiple sets of ridges and fractures. These peaks in the ice, which are typically 300 meters (1,000 feet) high and 800 meters apart, have remained an enigma since astronomers first spotted them in images taken by the Galileo spacecraft back in the 1990s. It's all to do with Europa's mysterious M-shaped double ridges. Schroeder is one of a trio of Stanford researchers who think they have the answer. The big question has been just how thick that icy crust is. “ life has a shot,” says Dustin Schroeder (Stanford University). If the icy shell is a thin veneer, it could contain pockets of water that interact with chemicals from space, other moons, and the volcanoes of Io (another of Jupiter's moons). There's more water under that ice than all of Earth's oceans, lakes, and rivers combined. The resulting tidal heating is enough to sustain a vast ocean of liquid water beneath Europa's icy crust. The gravitational might of Jupiter stretches and squeezes the satellite, which is almost as big as our own Moon. The results appear in Nature Communications.Įuropa has long been atop the solar system's habitability hit list. New radar measurements of Greenland's ice sheets here on Earth, and their similarity to features on the icy moon, suggest there could be water close to Europa's surface, something that would make for a more life-friendly environment. Jupiter's moon Europa, as imaged by NASA's Galileo spacecraftĪstronomers may have just taken a big step towards figuring out whether Jupiter's moon Europa is habitable.
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